Server or client problem?

Several friends tried to download a huge file from my local server (Blackmoon FTP Server, latest FREE release). All use SmartFTP 1.0.976. However after 30-60 minutes, SmartFTP issues for some reason (???) an ABOR command. Is this a problem with SmartFTP or the server?

I would say it's the server since many people get it on the same server, but the command seems to be issued by the clients (SmartFTP)

Here the log of the Blackmoon server:

Any ideas?

---- cut here ----

Version 2.6.2 Release 2 - Build 1687. Free Edition. Service Ready

...

Thu, Jun 26 (23:39:48) - 350 Restarting at 162904412. Send STORE or RETRIEVE to initiate transfer
Thu, Jun 26 (23:39:48) - RETR Hall.mpg
Thu, Jun 26 (23:39:48) - 150 File status okay; about to open data connection.
Fri, Jun 27 (00:27:29) -

Might it be that there is a connection timeout if SmartFTP is not registered?

TIA

If your data connection (transfer) timeouts (no data sent within x seconds) SmartFTP sends a ABORT to abort the data connection.

--- UNSURE ---
The server FTP software may not understand OOB commands.
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It's not related to the unlicensed version of SmartFTP.